1. Field of the Invention
This invention relates to an improved method for collecting yarn in automatic winding machines provided with guide members for the yarn being wound, which deposit the yarn in the form of bobbins on which the yarn is wound along a traversing path.
The invention relates particularly to yarn winding after its controlled cutting, this winding being required to take place within the central portion of the bobbin.
2. Discussion of the Background
It is known in the art that winding machines in general, and bobbin winding machines in particular, are provided with bobbin carrying arms. These arms consist essentially of a mandrel formed from a fixed fixing center and a movable fixing center, the purpose of which is to carry, center and fix the tube onto which the yarn is wound to form the bobbin, and to allow regular yarn winding.
The bobbin assumes either substantially cylindrical or substantially frusto-conical shapes. Frusto-conical shapes .are often formed in order to facilitate yarn unwinding during the subsequent fabric manufacture stages.
At each request for controlled yarn cutting it can occur that the yarn end is winding onto one of the two ends of the bobbin under formation and, quite frequently, the yarn--having its cut end suddenly without tension and uncontrolled--is deposited in the form of several turns about one of the fixing centers of the yarn carrying mandrel. Alternatively, that yarn portion which escapes from the side of a frusto-conical bobbin is deposited about the circumferential gripping line between the fixing center and the end of the tube.
During the next joining or knotting cycle it can occur that not all the yarn turns wound on the fixing center are gripped, unwound and removed by the suction port, on restarting the winding process the bobbin under formation again accumulates wound yarn, but there remains the presence of a more or less lengthy yarn portion extending beyond the side of the bobbin.
Even worse the suction port may be unable to suck-in the yarn end because it is too distant. The unit is then compelled to stop, to interrupt the winding process and to require the assistance of a service operator. The cost of this assistance and the reduction in the machine service factor considerably influence the production cost calculations. The efficiency of service operators is very low due to the randomness of the operations as opposed to programmed intervention.
A further serious drawback arises from the yarn portions extending outside the bobbin, which can compromise correct use of the .bobbin during its unwinding in subsequent processing.